The Planning, Programming, Budgeting, and Execution (PPBE) system has governed Department of Defense resource allocation for over 60 years. In support of a congressionally directed PPBE Reform Commission, this report reviews the PPBE phases, examines the development of key PPBE documents, analyzes the timelines involved in developing the President’s Budget Request and associated Future Years Defense Program and recommends priorities and options for improving the PPBE system.